1. Field of the Invention
The present invention relates a scanned document auto-detecting apparatus of detecting the presence of a scanned document without additional control circuit. Based on the decision result, a scanning procedure starts to degrade cost by removing the additional control circuit. The scanned document auto-detecting apparatus prevents users from running the scanning procedure wastefully when there is no scanned document.
2. Description of the Prior Art
As science goes on getting progress, many kinds of products are produced and modified each day, and a similar progress also occurs in optical systems such as scanners. There is a trend of mounting a scanner with higher resolution inside the case of a computer as a standard equipment.
Rollers are conventionally used to feed the scanned document into the scanner, wherein the rollers damage the surfaces of the scanned document when the scanned document is being fed. However, the roller-feeding scanner can not scan transparent documents such as lantern slides, and the rollers are easily dirtied by dust that will generate black or unusual color lines in images. In addition, the sizes of the mechanical and optical elements are not effectively degraded for achieving the purpose of mounting inside the case.
Another common scanning scheme is to put the scanned document inside a tray (or a cassette), and then feeds the scanned document for scanning. The tray (or the cassette) prevents the surface of the scanned document from being damaged by directly contacting. Paper jam that usually appears in the roller-feeding scanner is also overcome. In addition, the scheme does not need to clean dust frequently as the roller-feeding scanner does, and the convenience of operation is apparently upgrading.
There is an important function that a decision procedure is first applied to decide the presence of a scanned document. If the decision result indicates that the scanned document is absent then the scanning procedure will be terminated. Because a user may fail to put the scanned document inside the tray and start the scanning procedure, it is thus necessary for a scanner to avoid this situation.
An additional control circuit is conventionally applied as to perform a decision procedure, such as detecting the weight of the scanned document or checking existence indicating parameters for deciding the presence of the scanned document. Because the additional control circuit is completely irrelevant with the scanning procedure, which will require additional cost and spaces and thus increase the layout difficulty. Therefore, a detecting apparatus is needed as to automatically detect the presence of the scanned document.